In accordance with current commercial practice, resilient or flexible synthetic plastic surface coverings having a top coating or wear layer comprising one or more thermoplastic synthetic resins or polymers, one or more plasticizers, colorants or pigments in various patterns or designs, heat and light stabilizers, fillers, and other improvement agents and additives are widely used in sheet, film, or tile form for many purposes, particularly as surface coverings, primarily resilient floor coverings.
The patterns and designs and other decorative effects of such surface coverings are of prime importance in insuring the commercial acceptability of such surface coverings in the public marketplace. In recent years, there has been a great deal of interest in the creation of three-dimensional effects, or of stone terrazzo effects, and similar surface interest effects and textured appearances. Such effects and appearances are often obtained by blending opaque, translucent, or transparent, multicolored chips, flakes, or granules into the top coating or wear layer. Many processes and various forms of apparatus have been used hitherto in the manufacture of such surface coverings as noted in U.S. Pat. Nos. 3,152,002, 3.232,780, 3,239,364, 3,359,352, and 3,660,187.
However, many of these processes, although capable of producing excellent products of satisfactory commercial acceptability, have been complicated and many of the forms of apparatus used have been large, heavy, sometimes difficult to operate, and often quite expensive. One particular difficulty in prior procedures resided in the requirement or necessity of additional web monitoring equipment, such as the use of free loops, to control web back tensions. Such requirements or necessity and other objectionable features and disadvantages are avoided by the use of the apparatus and the process of the present invention.